Experimental and modelling evidence of splash effects on manure borne Escherichia coli washoff

Abstract

In tropical montane South-East Asia, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads. Land use change is also contributing to increased microbial pathogen dissemination and contamination of stream waters. Escherichia coli (E. coli) is frequently used as an indicator of faecal contamination.Field rain simulations were conducted to examine how E. coli is exported from the surface of upland, agricultural soils during runoff events. The objectives were to characterize the loss dynamics of this indicator from agricultural soils contaminated with livestock waste, and to identify the effect of splash on washoff. Experiments were performed on nine 1 m 2 plots, amended or not with pig or poultry manure. Each plot was divided into two 0.5 m 2 sub-plots.One of the two sub-plots was protected with a mosquito net for limiting the raindrop impact effects. Runoff, soil detachment by raindrop impact and its entrainment by runoff, and E. coli loads and discharge were measured for each sub-plot. The results show that raindrop impact strongly enhances runoff generation, soil detachment and entrainment and E. coli export.When the impact of raindrops was reduced with a mosquito net, total runoff was reduced by more than 50%, soil erosion was on average reduced by 90% and E. coli export from the amended soil surface was on average 3 to 8 times lower. A coupled physics-based approach was performed using the Cast3M platform for modelling the time evolutions of runoff, solid particles detachment and transfer, and bacteria transport that were measured for one of the nine plots. After estimation of the saturated hydraulic conductivity, soil erodibility, and attachment rate of bacteria, model outputs were consistent with measured runoff coefficients, suspended sediment and E. coli loads. This work therefore underlines the need to maintain adequate vegetation at the soil surface to avoid the erosion and export of soil borne potential pathogens towards downstream aquatic systems.

The Multiscale TROPIcal CatchmentS critical zone observatory M‐TROPICS dataset II: Land use, hydrology and sediment production monitoring in Houay Pano, northern Lao PDR

“…The dataset has been used: (1) to evaluate the role of slope on soil surface runoff production (Ribolzi, Patin, et al, 2011) and to interpret SPM and BPM sources and dynamics (Chaplot, Coadou le Brozec, et al, 2005, Chaplot, Rumpel, et al, 2005; Evrard et al, 2016; Gourdin, Evrard, Huon, Lefèvre, et al, 2014, Gourdin, Evrard, Huon, Reyss, 2014, Gourdin et al, 2015; Huon et al, 2017; Lestrelin et al, 2012; Valentin et al, 2008); (2) to assess the impact of land‐use change on catchment hydrology, soil erosion, and sediment yield (Chaplot et al, 2007; Huon et al, 2013; Patin et al, 2012, 2018; Pierret et al, 2007; Ribolzi et al, 2017, 2018; Vigiak et al, 2008); (3) to understand bacteria fate and transport (Boithias et al, 2016, 2021; Causse et al, 2015; Le et al, 2019; Ribolzi, Cuny, et al, 2011, Ribolzi et al, 2016; Rochelle‐Newall et al, 2016); (4) to understand weed seed transport by soil surface wash off and erosion (de Rouw et al, 2018); (5) to understand carbon and black carbon erosion (Chaplot et al, 2009; Rumpel, Alexis, et al, 2006, Rumpel, Chaplot, 2006, Rumpel et al, 2007, 2008, 2009); (6) to build models focused on hydrology and water quality issues at plot scale (Mügler et al, 2019, 2021) and at catchment scale (Abbas et al, 2020; Chaplot, Giboire, et al, 2005; Kim et al, 2017, 2018; Lacombe et al, 2016).…”

“…(3) to understand bacteria fate and transport (Boithias et al, 2016(Boithias et al, , 2021Causse et al, 2015;Le et al, 2019;Ribolzi, Cuny, et al, 2011Rochelle-Newall et al, 2016); (4) to understand weed seed transport by soil surface wash off and erosion (de Rouw et al, 2018); (5) to understand carbon and black carbon erosion (Chaplot et al, 2009;Rumpel, Alexis, et al, 2006, Rumpel et al, 2007; ( 6) to build models focused on hydrology and water quality issues at plot scale (Mügler et al, 2019(Mügler et al, , 2021 and at catchment scale (Abbas et al, 2020;Chaplot, Giboire, et al, 2005;Kim et al, 2017Kim et al, , 2018Lacombe et al, 2016).…”

The Fate of Foodborne Pathogens in Manure Treated Soil

“…Bacteria found in manures, e.g., E. coli and Salmonella, have often been implicated either directly or indirectly to outbreaks of human illness (Pell, 1997;Bicudo and Goyal, 2003;Guan and Holley, 2003;Hutchison et al, 2004). Viable pathogens contained within manure spread on agricultural land may be distributed by leaching, surface run-off, water source contamination and contaminated crop removal (Fenlon et al, 2000;Albihn and Vinnerås, 2007;Semenov et al, 2009;dikovic-Kolic et al, 2014;Alegbeleye and Sant'Ana, 2020;Mügler et al, 2021). A relationship therefore exists between agricultural practices and subsequent pathogen transfer to multiple ecosystems.…”

Biological Indicators for Fecal Pollution Detection and Source Tracking: A Review

“…A rainfall event can result in up to a three-fold increase of E. coli counts in recreational waters compared to before rainfall, and this increase can persist for up to 12 h [102,103]. After a rainfall event, increases in E. coli counts may occur due to the "first flush" from stormwater drainage or agricultural waste runoff coming along with the flow [103,104]. Furthermore, bacteria including E. coli tend to form flocs, adhere to rocks and other particles, then settle down to the sediment of freshwater ecosystems.…”